Several major British supermarkets have shifted away from selling true mackerel in canned products, opting instead for Chilean jack mackerel, a different species with lower nutritional value. This change, driven largely by sustainability concerns and declining North-East Atlantic mackerel stocks, has sparked debate among consumers and industry experts alike.

Princes, a key supplier for Tesco and J Sainsbury, transitioned its branded canned mackerel range to Chilean jack mackerel last year. Despite the similar name, Chilean jack mackerel (a Trachurus species within the Carangidae family) is distinct from true mackerel, which belong to the Scombridae family under the genera Scomber or Rastrelliger. According to product packaging, Chilean jack mackerel contains roughly half as much omega-3 fatty acids and about 100 fewer calories per 100 grams compared to true mackerel. Some consumers have also noted changes in taste and texture, with descriptions of the substitute fish as less oily and bearing a metallic smell.

Lidl has also been progressively replacing its mackerel offerings with sustainably sourced Chilean jack mackerel, while Waitrose ceased sourcing fresh, chilled, and frozen true mackerel in April. The latter is in the process of phasing out canned true mackerel products as existing stocks deplete.

These shifts come amid a protracted international dispute over mackerel quotas known as the “mackerel war,” involving the UK, Iceland, Greenland, Norway, the Faroe Islands, the EU, and Russia. North-East Atlantic mackerel catches have exceeded scientific recommendations by 39% since 2010, leading to an estimated 75% decline in stocks over the past decade, according to the International Council for the Exploration of the Sea (ICES). As a result, the fishery has lost Marine Stewardship Council (MSC) certification—a key sustainability marker valued by retailers. In contrast, Chilean jack mackerel remains MSC-certified.

Experts warn that unresolved quota disputes threaten the mackerel stock’s recovery. Tim Gray, a professor of political thought at Newcastle University specializing in fisheries management, described the situation as “a mess” that endangers the species’ survival, with little progress toward a resolution.

This trend away from true mackerel is not confined to the UK; major supermarkets across Europe—including Albert Heijn and Jumbo in the Netherlands, and Axfood in Sweden—have curtailed sales of true mackerel in favor of jack mackerel alternatives.

In response to labeling concerns, the UK’s Department for Environment, Food and Rural Affairs (Defra) updated regulations last December to permit the marketing of Trachurus species as “jack mackerel,” shortly after Princes rebranded its products accordingly. Defra emphasized its commitment to sustainable fish stocks and noted that jack mackerel cannot be marketed as “Atlantic” mackerel. Critics argue the policy change risks confusing consumers by blurring distinctions between species.

Industry voices have expressed disappointment at reliance on imported fish. Stewart Harper, former managing director of North Atlantic Fishing Company, said consumers lose out nutritionally and gastronomically by substituting true mackerel with jack mackerel sourced from distant waters. Wholesale costs for Chilean jack mackerel run about one-third those of Atlantic true mackerel, though retail prices have remained largely comparable. For example, Tesco sells Princes’ jack mackerel for £1.75 a tin and true mackerel for £1.95.

European authorities have singled out overfishing by Russia as a significant factor in the depletion of North-East Atlantic mackerel stocks. The mackerel quota dispute escalated earlier this year when ICES recommended reducing the 2026 catch by about 70% to 174,357 tonnes. Instead, the UK, Norway, Iceland, and the Faroe Islands agreed on a provisional quota approximately 72% above the scientific advice, at 299,010 tonnes—drawing strong criticism from the European Commission. Negotiations between these coastal states and the EU remain unresolved.

Rising sea temperatures have pushed mackerel further north, increasing the stock’s presence in Icelandic and Faroese waters and prompting shifts in quota demands by those countries. Brexit added complexity by positioning the UK as an independent coastal state, renegotiating its share separately.

Aoife Martin, executive chair of the North Atlantic Pelagic Advocacy Group, characterized the ongoing disputes not merely as fishing issues but as broader failures of international fisheries governance, underscoring the urgent need for cooperative solutions to safeguard mackerel stocks for the future.